Suction tube for a vacuum cleaner

ABSTRACT

The present invention provides a suction tube for a vacuum cleaner, which comprises an outer pipe ( 8 ), an inner pipe ( 1 ) received in the outer pipe, and a locking device ( 20 ) disposed between the inner pipe ( 1 ) and the outer pipe ( 8 ). A guiding bush ( 2 ) is provided at the inner wall of the outer pipe ( 8 ). The inner pipe ( 1 ) is provided with a row of detent holes ( 9 ) which are arranged in the axial direction of the inner pipe ( 1 ). An inner liner tube ( 12 ) is fixed onto the inner wall of the inner pipe ( 1 ). Thus, the manufacturing of the detent recesses becomes easier since the detent holes are made through the inner wall of the inner pipe, and the air leakage of the inner pipe due to the detent holes can be prevented by the inner liner tube ( 12 ) provided at the inner pipe ( 1 ).

FIELD OF THE INVENTION

The present invention relates to a vacuum cleaner, and moreparticularly, to a suction tube for a vacuum cleaner.

BACKGROUND OF THE INVENTION

A conventional suction tube for a vacuum cleaner comprises an outerpipe, an inner pipe inserted into the outer pipe, a guiding bushdisposed at the outer pipe, a plurality of detent recesses axiallyprovided at the outer surface of the inner pipe, and a locking devicedisposed between the inner pipe and the outer pipe. The detent recessescontains a locking pin roller which can be inserted into one of thedetent recesses. The locking pin roller has a mantle at its top forkeeping the locking device in its locking state. The locking pin rollercan move upward out of the recess to make the locking device unlocked,when the mantle is removed. As a result, the inner pipe can be movedaxially with respect to the outer pipe. Guiding slopes are provided atthe front and rear edges of the detent recesses so as to help thelocking pin roller be released from the detent recess easily. However,the locking pin roller is liable to escaping from the detent recessalong the guiding slopes under an impact arisen between the inner pipeand the outer pipe. In this case, the locking device will fail to work.

To overcome the above drawbacks, Chinese patent No. 01266578.9 providesa telescopic suction tube for a vacuum cleaner, in which an inner pipeof this telescopic suction tube is provided with a plurality of detentrecesses. The sidewalls of the detent recesses-are perpendicular to theouter surface of the inner pipe. Although such detent recesses make thelocking device thereof be capable of withstanding heavier impact, theyare likely to crack at a portion between the sidewall of the recess andthe bottom thereof perpendicular to the sidewall arisen by a stressgenerated from the manufacturing thereof. As a result, air leakage willhappen to the inner pipe and the vacuum degree in the inner pipe of thevacuum cleaner will be decreased accordingly, when the vacuum cleaneroperates.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a suction tube for avacuum cleaner having detent recesses that are easy to manufacture. Thesuction of the invention is capable of withstanding a heavy axialimpact.

The suction tube of the present invention comprises an outer pipe; aninner pipe received in said outer pipe; a locking device having andetent pin for latching said inner pipe with respect to said outer pipe;a guiding bush attached to said outer pipe; a first guiding memberdisposed on said guiding bush for guiding said inner pipe and said outerpipe to move axially with respect to each other; a second guiding memberdisposed on said inner pipe for guiding said inner pipe and said outerpipe to move axially with respect to each other, said first guidingmember and second guiding member are engageable and slidable with eachother, characterized in that:

said inner pipe is provided axially with a row of detent holes, each ofwhich penetrates through the wall of the inner pipe, an inner linerlayer is fixed onto the inner wall of said inner pipe for isolatingvacuum of the inner pipe from the detent holes, said detent pin of saidlocking device inserts into one of said detent holes when said lockingdevice is in a locking state, while disengages with the detent hole whensaid locking device is in an unlocking state.

The present invention is advantageous over the prior arts in that themanufacturing of the detent holes becomes easier since these recessesare made penetrating through the inner wall of the inner pipe, and theair leakage on the inner pipe due to such penetrating of the detentrecesses can be prevented by the inner liner layer provided on the innerwall of said inner pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described withreference to the drawings, in which:

FIG. 1 shows a partial cross-sectional view of an embodiment of thesuction tube of the present invention in the locking state;

FIG. 2 shows a partial cross-sectional view of an embodiment of thesuction tube of the present invention in the unlocking state;

FIG. 3 shows a cross-sectional view taken along line A-A as shown inFIG. 1;

FIG. 4 shows a cross-sectional view taken along line B-B as shown inFIG. 1;

FIG. 5 shows a cross-sectional view taken along line C-C as shown inFIG. 2; and

FIG. 6 shows a top view of an inner pipe of the suction tube accordingto the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Referring to FIG. 1 to FIG. 6, a suction tube for a vacuum cleaner ofone embodiment of the invention comprises an outer pipe 8 having alarger portion 81 and a smaller portion 82, an inner pipe 1 which isreceived in the outer pipe 8, and a locking device 20 disposed at theouter pipe 8 for latching the inner pipe 1 with respect to the outerpipe 8. A guiding bush 2 is fixed to the inner wall of the portion 81 ofthe outer pipe 8 where it has a larger diameter than the smaller portion82. A first guiding member and a second guiding member are respectivelydisposed at the guiding bush 2 and the inner pipe 1 for guiding theinner pipe 1 to move axially with respect to the outer pipe 8. The twoguiding members are engageable and slidable with each other, so that theinner pipe 1 is axially movable but unrotatable when moving in the outerpipe 8. A row of detent holes 9 are provided axially at the inner pipe1. Each of the holes 9 penetrates radially through the wall of the innerpipe 1. An inner liner layer, which is an inner liner tube 12 in thisembodiment, is fixedly disposed at the inner surface of the wall of theinner pipe 1.

As shown in FIGS. 1 and 2, in this embodiment, the locking device 20includes a detent pin 6. When the detent pin 6 is inserted into one ofthe detent holes 9, the locking device is in a locking state (FIG. 1),and when it disengage with the detent holes 9, the locking device is ina unlocking state (FIG. 2).

Also referring to FIG. 1 and FIG. 2, the locking device 20 furthercomprises a detent pin boss 3 fixed to the outer pipe 8, a spring 5connected to the detent pin 6, and a detent shifting fork 10 connectedto the detent pin 6 with one end and the middle part thereof connectedrotatably to the detent pin boss 3. The detent pin 6 is slidable in theradial direction of the outer pipe 8 for inserting into the detent pinboss 3 and the holes 9. The locking device provides a casing 4 connectedto the outer pipe 8. Another end of the detent shifting fork 10 extendstoward out of a hatch of the casing 4 and forms a button 7. When theoperator presses the button 7, the end of the detent shifting fork 10 towhich the detent pin 6 is connected overcomes the elastic force of thespring 5 to lift the detent pin 6 by means of a pivot 101, therebyswitching the locking device 20 from the locking state into theunlocking state.

The second guiding member is a guiding slot 13 axially disposed at theouter wall of the inner pipe 1, and the first guiding member is aguiding rib 11 which is disposed at the inside wall of the guiding bush2 and protrudes toward its axial center. The guiding rib 11 is disposedin the guiding slot 13 and is slidable therein. As shown in FIG. 6, arow of the detent holes 9 are provided at the guiding slot 13.

As shown in FIG. 4, the inner liner tube 12 provides at its outside walla groove 14 extending axially and facing toward the detent holes 9.

There exists a clearance 121 between the outer surface of the innerliner tube 12 and the inner surface of the inner pipe 1. The clearance121 in the present embodiment is the groove 14. When the locking deviceis in the locking state, the detent pin 6 penetrates through one of thedetent holes 9 and inserts into the clearance. Therefore, it is notliable for the detent pin 6 to escape from the detent hole 9 when theouter pipe 8 and the inner pipe 1 encounter an axial impact, therebyensuring a reliable locking state between the inner pipe 1 and the outerpipe 8. The inner liner tube 12 is provided with end sealing members attwo ends of the groove 14. The end sealing members block at both ends ofthe groove 14 the clearance between the outer wall of the inner linertube 12 and the inner wall of the inner pipe 1. Thus, the portions ofthe inner pipe 1 where air leakage is liable to occur due to the detentholes are sealed by the end sealing members 15 and the inner liner tube12. When the vacuum cleaner works and the airflow with negative pressureis flowing in the inner liner tube 12, no air will leak through thedetent holes 9 into the inner liner tube 12.

1. A suction tube for a vacuum cleaner comprising: an outer pipe (8); aninner pipe (1) received in said outer pipe (8); a locking device (20)having a detent pin (6) for positioning said inner pipe (1) with respectto said outer pipe (8); a guiding bush (2) attached to said outer pipe(8), a first guiding member disposed at the guiding bush (2); and asecond guiding member attached to said inner pipe (1), being engageableand slidable with said the first guiding member so that said inner pipe(1) and said outer pipe (8) can move axially with respect to each other,characterized in that said inner pipe (1) is provided axially with a rowof detent holes (9), each of which penetrates through the wall of theinner pipe (1), an inner liner layer is fixed onto the inner wall ofsaid inner pipe (1) for isolating vacuum of the inner pipe from thedetent holes, said detent pin (6) of said locking device is insertedinto one of said detent holes (9) when said locking device (20) is in alocking state, and disengages with the detent hole when said lockingdevice (20) is in an unlocking state.
 2. A suction tube for a vacuumcleaner as claimed in claim 1, wherein said locking device furthercomprises a detent pin boss (3) fixed to said guiding bush (2), a spring(5) connected to the detent pin (6), and a detent shifting fork (10)whose one end is connected to the detent pin (6) and the middle partthereof is connected rotatably to the detent pin boss (3).
 3. A suctiontube for a vacuum cleaner as claimed in claim 2, wherein said lockingdevice includes a casing (4) having a hatch at its side, and the otherend of said detent shifting fork (10) extends toward out of the hatch ofthe casing (4) and forms a button (7).
 4. A suction tube for a vacuumcleaner as claimed in claim 1, wherein said second guiding member is aguiding slot (13) axially disposed at the outside wall of said innerpipe (1), and said first guiding member is a guiding rib (11) axiallydisposed at the inside wall of said guiding bush (2) and slidably movedwithin said guiding recess (13).
 5. A suction tube for a vacuum cleaneras claimed in claim 4, wherein said detent holes (9) are disposed atsaid guiding slot (13).
 6. A suction tube for a vacuum cleaner asclaimed in claim 1, wherein said inner liner layer is an inner linertube (12) which is provided at its outer wall with a groove (14)extending axially along said inner liner tube (12) and facing saiddetent holes (9).
 7. A suction tube for a vacuum cleaner as claimed inclaim 6, wherein a clearance is provided between the outer surface ofthe inner liner tube (12) and the inner surface of the inner pipe (1),and when the locking device (20) is in the locking state, the detent pin(6) penetrates through one of the detent holes (9) and inserts into theclearance.
 8. A suction tube for a vacuum cleaner as claimed in claim 6,wherein said inner liner tube (12) is provided with end sealing membersat two ends of said groove (14) to block the clearance between the outerwall of said inner liner tube (12) and the inner wall of said inner pipe(1).